The invention relates to a process for the recovery of solubilized nonionic glucan in a solution. Further, the invention relates to employing a divalent cation at an alkaline pH to recover the solubilized nonionic glucan from solution.
Current procedures teach the use of a water miscible organic solvent such as isopropyl alcohol or acetone for the recovery of nonionic polysaccharides, in particular glucan from fermentation media and other glucan containing solutions. As practiced, the clarified media is concentrated to a flowable viscosity and precipitated with 50% by volume solvent. The precipitate is drained and then successively treated with higher concentrations of the water miscible organic solvent. This process which requires the media volumes to be reduced and concentrated and large quantities of solvent is an expensive, capital intensive procedure.
U.S Pat. No. 3,759,896 discloses a process to produce polysaccharides with antitumor activity mainly consisting of B-(1.fwdarw.3)-linked D-glucose residue by obtaining culture filtrates of fungi belonging to Ascomycetes, Basidiomycetes and Fungi imprefecti and then purifying the culture filtrate by sequential treatments of acidification, deionization by ion exchange resins and precipitation with a water soluble miscible solvent.
U.S. Pat. No. 4,072,567 discloses a process for producing a water-insoluble glucan by cultivating a Streptococcus microrganism in a liquid medium and recovering the glucan by sedimentation, filtration or seiving. The crude glucan is further processed by dissolving in sodium hydroxide, centrifuging, neutralizing with hydrogen chloride and then washing.
Xanthan gum, an anionic polysaccharid, is a fermentation product of the bacteria Xanthomonas campestris. The gum is recovered from the fermentation broth by salt precipitation. Known precipitating agents for the gum include quarternary amine salt precipitation (U.S. Pat. No. 3,119,812); aluminum salt precipitation (U.S. Pat. No. 4,051,317); amine salt precipitation (U.S. Pat. No. 4,254,257) and alkaline precipitation in the presence of divalent cations (U.S. Pat. No. 3,382,229). However, xanthan gum is structurally distinct from nonionic glucons.
It is desirable to find novel methods to recover glucans from solution. Further, it is desirable to reduce recovery costs of glucan as an economic improvement for commercializing a process to recover glucans.
Polysaccharides have been used extensively in the food, cosmetic, paper, pharmaceutical, oil and chemical manufacturing industries. The process of the instant invention is useful in that polysaccharides, in particular glucans are useful as viscosifiers, binders, thickners and stabilizers in industrial and food applications. Glucans have various industrial applications such as enhanced oil recovery and oil well drilling muds, tablet coatings, opthalmic solutions, anti-acid suspensions, porcelain and ceramic glazes, ceramic binders, water-based paints, paper coatings, printing inks, integrated circuit chips, agricultural seed coatings, pesticide sprays and the like.
It is an object of the instant invention to recover nonionic polysaccharides, in particular glucans from solution. It is another object of the instant invention to recover solubilized glucan from solution by precipitating the glucan from the solution with a divalent cation at an alkaline pH.
These and other objects, together with the advantages over known methods shall become apparent from the specification which follows and are accomplished by the invention as herein described and claimed.